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RFC-Interview Questions & Answers-SAP ABAP-4.

16. What Is Fast RFC (fRFC)?

Fast RFC is a type of RFC used for system internal communications. Interactions between J2ee engine in SAP & the ABP runtime environment in the same instance are done using Fast RFC. This type of RFC is possible only if both the source & target are on the same system.

17. What Is Parallel Processing In RFC (pRFC)?

Parallel Processing is an extension of aRFC. Generally when we call a function module, it will stop the current program, execute another (called) program and then returns control to original program and again original program starts execution.

With asynchronous function module control will start parallel without stopping the current program from which you called the function module. Parallel processing is generally used when there is a need to process large amount of data.

In parallel processing, a job step is started as usual in a background processing work process. A program that runs in a job step can be programmed to use a special variant of asynchronous RFC to have portions of the data to be processed run in parallel in other work processes. You can recognize such a program by its use of the CALL FUNCTION STARTING NEW TASK DESTINATION IN GROUP instruction to start the function modules that process the data.

While the job itself runs in a background process, the parallel processing tasks that it starts, run in dialog work processes. Such dialog work processes may be located on any SAP server. Parallel processing has been implemented in some SAP applications that have long-running reports.

18. What Are The Features Of Transactional RFC (tRFC)?

Some of the salient features of tRFc are:

tRFC guarantees that a called function module is executed in the target system exactly once.

All tRFC calls terminated with the statement COMMIT WORK belong to one LUW (Logical Unit of Work). Each LUW automatically receives a transaction ID.

Within an LUW, all function modules are executed in the target system in the sequence in which they are called in the send system.

tRFC calls with the addition AS SEPARATE UNIT map a separate LUW each in the target system. Such a sub LUW contains exactly one tRFC call and is processed independent of the actual (superior) LUW. This sub LUW receives its own transaction ID.

If within an LUW several destinations are used, all tRFC calls that belong to one destination also form a sub LUW. However, since this bundling happens only internally, there is no separate transaction ID assigned to the sub LUW.

19. What Are the Disadvantages of Transactional RFC (tRFC)?

Some of the disadvantages of tRFC are:

tRFC processes all LUWs independent of one another. Due to the amount of activated tRFC processes, this procedure can reduce performance significantly in both the send and the target systems.

In addition, the sequence of LUWs defined in the application cannot be kept. Therefore, there is no guarantee that the transactions are executed in the sequence dictated by the application. The only guarantee is that all LUWs are transferred sooner or later.